Sparkle-brain: the brain 'hyperactivates' at the thought of kilojoule-rich foods.

Our brain's reward system doesn't just light up, it "hyperactivates".

Our brain does its dopamine dance, not just for cupcakes, but for cheesecake, chocolate, bacon and other 'fun' fatty foods.

If your mouth is salivating at the thought of those foods, that's because your brain's sparkly anticipatory reward system is being activated.

We eat brussel sprouts, on the other hand, and despite the nutrients it bestows on our body's cells, our brain's reward system kind of goes "meh!"

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It is a problem that has plagued obesity experts because it propels people towards unhealthy choices.

But a new small study suggests it may be possible to teach our brains to sparkle over brussel sprouts and shimmy-down cravings for the cupcakes.

"We don't start out in life loving french fries and hating, for example, wholewheat pasta," said co-author Susan B. Roberts. "This conditioning happens over time in response to eating – repeatedly – what is out there in the toxic food environment."

Scientists have been concerned that such conditioning is incredibly hard, if not impossible to reverse. However, this new research, published in the journal Nutrition and Diabetics, demonstrates otherwise.

To find out whether we can retrain our brain's response to healthy foods, researchers from Tufts University and Massachusetts General Hospital monitored the reward system part of the brain in 13 obese participants over six months.

Eight of the participants were put on a new weight-loss program devised by Tufts University and comprising "low-glycaemic index carbohydrates with higher fibre and higher protein" foods along with support sessions addressing meal planning, goal setting and motivation.

The remaining five participants made up the control group, who could go cupcake crazy.

All participants had their brains scanned before and after the six-month program. During the scans they were shown and asked to rate the desirability of pictures including kilojoule-laden foods such as french fries, Fruit Loops and fried chicken as well as low-kilojoule foods like sweet potato and grilled chicken.

By the end of the program, the intervention group "achieved significant weight loss versus controls". Their brains also began to sparkle differently; "fun" foods became less desirable while their brains danced more in anticipation of eating the healthier foods.

The authors acknowledged the limitations of the study, including the small sample size and the fact that "the regulation of food intake via reward systems is clearly complicated".

But they are excited about the sparkle shift in neural responsivity and what this might mean for treating obesity.

"Although other studies have shown that surgical procedures like gastric bypass surgery can decrease how much people enjoy food generally, this is not very satisfactory because it takes away food enjoyment generally rather than making healthier foods more appealing," co-author Thilo Deckersbach said.

"We show here that it is possible to shift preferences from unhealthy food to healthy food without surgery and that MRI is an important technique for exploring the brain's role in food cues.

"There is much more research to be done here, involving many more participants, long-term follow-up and investigating more areas of the brain. But we are very encouraged that the weight-loss program appears to change what foods are tempting to people."